Stators are already known in the art, wherein the permanent magnet system is formed by a single cylindrical permanent magnet which is provided with a bore and which is radially magnetized. Such a stator, however, is relatively expensive since the manufacture of correspondingly permanent magnets is very complicated.
In order to reduce the costs of manufacture, attempts have already been made with the aim to fix a number of permanent magnets around an inner magnetic conductive piece. This, however, requires a precise treatment of the surface of the permanent magnets and of the magnetically conductive piece, and thus the reduction of the costs of manufacture is very poor.